Safety shut down for conveyor systems



March 19, 1957 T. F. MURPHY HAL 2, 8 ,7

SAFETY SHUT DOWN FOR CONVEYOR SYSTEMS Filed Dec. 16 1953 2 Sheets-Sheet1 LOCK ou-r LIMIT SWITCH SWITCH THOMAS P. MURPHY EDWARD A. MURPHY IN VENTORS March 19, 1957 T. F. MURPHY EI'AL 2, 85,793

SAFETY snow DOWN FOR CONVEYOR SYSTEMS Filed Dec. 16 1953 2 Sheets-Sheet2 THOMAS P. MURPHY EDWARD A. MURPHY IN V EN TORS (LIE United StatesPatent SAFETY SHUT DOWN FOR CONVEYOR SYSTEMS Thomas F. Murphy,Preakness, and Edward A. Murphy, Belleville, N. J.

Application December 16, 1953, Serial No. 398,534

Claims. (Cl. 198-232) This invention relates to conveyors or conveyorsysteins and more particularly to a safety shut down mechanism whichwill shut down the feeding conveyors and other feeding means when thekey conveyor in the system is stopped by breakage of parts, clogging orother conditions which will eifect stoppage of proper operation thereof.I

More specifically the present invention comprises a safety shut downmechanism for conveyor systems embodying a shear pin incorporated in thedrive to the key conveyor in a system, which mechanism will uponbreakage of the shear pin cut off the operating power to the keyconveyor, and to the conveyors or mechanism feeding material to the keyconveyor, thereby eliminating seri ous breakage of parts, excessivepiling up of material being conveyed, etc., with elimination of theexpense contingent with the correction of such undesirable conditions.

With these and other objects in view, as may appear from theaccompanying specification, the invention consists of various featuresof construction and combination of parts, which will be first describedin connection with the accompanying drawings, showing a safety shut downfor conveyor systems of a preferred form embodying the invention, andthe feature forming the invention will be specifically pointed out inthe claims.

In the drawings: 7

Figure 1 shows a diagrammatic view of a conveyor system of the type towhich the present invention is employed.

Figure 2 is a diagrammatic view of the electrical circuit embodied inthe conveyor system together with the safety shut down portion of thecircuit.

Figure 3 is an end elevation of the safety shut down mechanism showingit applied to a fragment of a conveyor.

Figure 4 is a cross section of the line 4-4 of Figure 3 of the drawingsshowing the safety shut down mechanism in plan view.

In Figure 1 of the drawings a conveyor system is illustrateddiagrammatically of the type which is employed in foundries for servingthe dual purpose of separating the mold sand from castings and conveyingthe castings from the pouring floor to any desired point fortransportation to locations for the chipping and machining of thecastings. In this form of a conveyor system the sand and casting fromthe flasks are dumped first into a dump box shaker structure 1 whereinthe sand and castings are initially separated and part of the sand isshaken loose from the castings. From the dump box shaker 1, the sand andthe castings fall on the first of the feeder conveyors 2. The conveyor 2delivers the sand and castings to a second feeder conveyor 3. From thesecond feeder conveyor 3 the sand and castings are delivered to the keyconveyor 4 of the system where the sand falls off the lower end of theconveyor floor into a suitable receptacle or other conveying system andthe castings with Such sand as still is clinging thereto are delivered'ice V to' the final shaker 5 where the final separation of the sand andcastings is provided and from which the castings are taken forwithdrawal to any place for further work thereon such as cleaning,chipping or machining while the final sand is delivered from the shaker5 to any suitable point which may be an additional conveyor system (notshown) carrying the sand back to a point for reuse.

In conveyor systems of this type in foundries, the metal castings andsand are dumped by laborers into the ini tial dump box shaker 1 as thecastings cool in the flasks and oftentimes an excessive amount ofcastings are delivered which cause clogging of the conveyor system oroverloading of the conveyor system with the result in breakage of partsetc. When any such undesirable conditions occur the castings and sandpile up on the con veyors resulting in further breakage, or spillage ofthe castings and sand off the sides of the conveyors as Well as otherundesirable conditions which result in considerable expense for cleaningup and getting the conveyor system back in working conditions. Thepresent invention embodies means for automatically shutting down theoperation of the key conveyor and the feeding conveyors as well as thedump box shaker so as to prevent feeding of additional castings and sandto the key conveyor 4 in the event of stoppage of this conveyer for anypurpose or reason whatsoever.

, In the conveyor system shown and in other companionable conveyorsystems each of the different units such as a dump box shaker 1 thefeeding conveyors 2 and 3 and the key conveyor 4 are each operated byindependent electric motors indicated at 6. Referring to Figure 2, eachmotor has a starting circuit for individually energizing the motorcircuit. The individual starting circuits for each motor are interlockedwith one another such that those of conveyors 4, 3 and 2 and shaker box1 are 'circuit to the motor 6 of the key conveyor 4. The diagrammaticcircuit shown in Figure 2 shows the individual motor controllingcircuits with the circuit 11 for the dump shaker 1, the circuits 12 and13 for the feeding conveyors 2 and 3 connected in the circuit in advanceof the circuit 14 for the key conveyor 4 and the circuit 15 for theshaker 5 so that the lockout switch 10 will affect only the circuits 11,12, 13 and 14 to cut off the flow of energizing electrical current tothe motor 6 of the different units in advance of the key conveyor 4.

The lockout switch 10 is of any approved construction of electricalswitch which may be purchased on the open market and it is operated by arelatively long arm 16 connected to the switch and extending laterallyfrom one side of the switch. The switch arm 16 is of course of the usualpivoted type and is mounted -to swing laterally of the axis of avertical plane extending through the switch 10 in other words referringparticularly to Figure 4 of the drawings the arm 16 is mounted to moveoutwardly to open the switch 10 to cut off the flow of electrical energythrough the circuit upstream of the lockout switch 10. The arm 16 has adisc 17 attached to its outer free end which is engaged by a pin 18carried by the head 19. The head 19 is mounted on one end of an L-shapedarm 20. The arm 20 is slidably carried by suitable guide 21 which is inturn carried by or mounted on a driving element 22. The driving element22 is keyed on the shaft 23 which is the driving shaft of the keyconveyor 4 and it is connected to a driven element 24. The drivenelement 24 is connected to the driving chain 25 of the conveyor 4 andthe driving and driven elements 22 and 24 are connected by a shear pin26 so that when the driving l men 22is driven bya-the motor 6 thruthesha'ft' 23$ theconnection of the shear pin'26 will cause the drivenelement24 to drive the chain 25 of the conveyor 4. new-- ever, inrtheevent of clogging or stoppage of the conveyor 4 for any reason thechain25 will of course stop, its move, ment, which will stop movement of thedriven member 24. The' driving member 22 continuing'to be driven by 5the motor 6 will exert a stress upon the shear pin 2d which a will breakthis pin, thereby breaking connection between driving element 22 and thedriven element 24 and consecam surface '27 formed thereon on which aroller 28 .10 quently' cause. the element 22 to rotate independently ofa the element 24; The driven element 24 has an inclined Carried bythesli able arm 20 rests. So long. asfthe driven a the cam'surfaceffl'and'move the slidable armlfl. out; wardly co sing'the switcharm 16 to be moved. outwardly to break the electricalicircuitthruthelockout switch 1'0.v 7 and consequently cut ofi'the supply ofoperating electrical energy to the motors 6 of all'of theaunits inadvance of the s key conveyor 4; '7 7 If it is so desired a protectivehousing 30 be mounted about theelements 22 and 24 etc. to protectthemfrom fallingfisand, dust or the like.

Whilein the foregoing description, the safety shut down system ofconveying is shown and described as particu 'larly'applicable' for usein casting conveying and cleaning systems in foundries, it is to beunderstood that the safety shut down above described and shown in thedrawings may be employed in connection with any suitable type ofconveyor'system*utilizing what might be in effect 3 key conveyor; and a seriesof one or more convcyors rfeediiig material to the-key conveyor so thatupon stoppageof the-key conveyor all of the mechanism in advance or UPstream of -the' key conveyor would be stopped,

It'will be-nn'derstood' that the invention is not to be limited tothe'specific construction or arrangement of Parts 7 shown, but that'thcymay be widely modified within the invention as defined by the claims.

What-is claimed is: 1. In a conveyor system having aplurality ofconveyors,

driving means for each said conveyor, a control system for said drivingmeans including therein a lcick-outswitchflnd at least one of the saidconveyors operated by a dnivenv member connected thereto and furtherconnected by a' shear pin to a driving member fixed to the shaft of *adriving means, and a lock-out switch actuating means comprising a camsurface on the said driven member and an axially slidable arm mounted onthe said driving member and having one end adapted to engage the saidcam surface and the other end adapted to open the said lock-out switchwhen the shear pin breaks.

2. The system of claim 1 wherein the axially slidable arm is L-shapedand said other end of the arm is disposed in alignment with the axis ofsaid shaft.

3. The system of claim -1 wherein the-cut-out switch has a pivotedarmadapted to be movcdbysaid other end of the slidable arm;

4. The system of claim 1 whereinsaid cam surface ex tends on the drivenmember adjacent the shearing pin.

5. In a conveyor system having aplurality 'ofwconveyors, electricrmotorsfor driving said conveyors, circuits in series to energize each of thesaid electric motorsand-including therein a lock-out switch fordeencrgizing said motors, said, switchhavinganarm pivoted at one endthereof, and at; least one of the said conveyors operatedby a dr'i-ven.member connected thereto and further connected by a shear pin to adriving member. fixed to theshaft of an electric motor, and a lock-outswitch actuating means; comprising a cam surface on the said drivenmember, said cam surface extending transversely of said shaft and vdis--posed on the driven member adjacent the shearpin, and an, axiallyslidable arm mounted on said driving member and, having one end adaptedto engage said cam-surface and. the-other end of said arm being disposedin alignment with the axisof said shaft and adapted to move said pivotedswitch arm when the shear pin breaks to open said switch and stop saidconveyorsystem.

References Cited in thefile. of this-patent I UNITED STATES PATENTSChristensen -Sept.- 22,- 1953

